Accumulated Other Comprehensive Income - Components (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	$ (1,898)	$ (3,193)
Other comprehensive income / (loss) before reclassifications	(112)	50
Amounts reclassified from accumulated other comprehensive income	6	551
Other comprehensive income / (loss)	(106)	601
Balance at end of period	(2,004)	(2,592)
Defined benefit plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(768)	(1,464)
Other comprehensive income / (loss) before reclassifications	10	(4)
Amounts reclassified from accumulated other comprehensive income	20	53
Other comprehensive income / (loss)	30	49
Balance at end of period	(738)	(1,415)
Foreign currency translation
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(1,158)	(1,759)
Other comprehensive income / (loss) before reclassifications	(78)	(25)
Amounts reclassified from accumulated other comprehensive income	0	553
Other comprehensive income / (loss)	(78)	528
Balance at end of period	(1,236)	(1,231)
Gains and losses on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	28	30
Other comprehensive income / (loss) before reclassifications	(44)	79
Amounts reclassified from accumulated other comprehensive income	(14)	(55)
Other comprehensive income / (loss)	(58)	24
Balance at end of period	$ (30)	$ 54